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Article
Publication date: 1 April 1990

Clive Williams

Outlines some basic forms of dynamic loading which causevibrational problems in structures. Presents information on thepossibility of structural damage occurring from vibration

Abstract

Outlines some basic forms of dynamic loading which cause vibrational problems in structures. Presents information on the possibility of structural damage occurring from vibration. Discusses the human response in terms of its often being the limiting factor in terms of amplitude which can be tolerated within a structure. Details industrial vibrational problems, covering areas of traffic, piling, forced vibration and industrial plant.

Details

Structural Survey, vol. 8 no. 4
Type: Research Article
ISSN: 0263-080X

Keywords

Article
Publication date: 12 October 2022

Yongliang Wang, Jiansong Hu, David Kennedy, Jianhui Wang and Jiali Wu

Moderately thick circular cylindrical shells are widely used as supporting structures or storage cavities in structural engineering, rock engineering, and aerospace engineering…

Abstract

Purpose

Moderately thick circular cylindrical shells are widely used as supporting structures or storage cavities in structural engineering, rock engineering, and aerospace engineering. In practical engineering, shells often work with micro-cracks or defects. The existence of micro-crack damage may result in the disturbance of dynamic behaviours and even induce accidental dynamic disasters. The free vibration frequency and mode are important parameters for the dynamic performance and damage identification analysis. In particular, stiffness weakening of the local damage region leads to significant changes in the vibration mode, which makes it difficult for the mesh generated in the conventional finite element method to capture a high-precision solution of the local oscillation.

Design/methodology/approach

In response to the above problems, this study developed an adaptive finite element method and a crack damage characterisation method for moderately thick circular cylindrical shells. By introducing the inverse power iteration method, error estimation, and mesh subdivision refinement technique for the analysis of finite element eigenvalue problems, an adaptive computation scheme was constructed for the free vibration problem of moderately thick circular cylindrical shells with circumferential crack damage.

Findings

Based on typical numerical examples, the established adaptive finite element solution for the free vibration of moderately thick circular cylindrical shells demonstrated its suitability for solving the high-precision free vibration frequency and mode of cylindrical shell structures. The any order frequency and mode shape of cracked cylindrical shells under the conditions of different ring wave numbers, crack locations, crack depths, and multiple cracks were successfully solved. The influences of the location, depth, and number of cracks on the disturbance of dynamic behaviours were analysed.

Originality/value

This study can be used as a reference for the adaptive finite element solution of free vibration of moderately thick circular cylindrical shells with cracks and lays the foundation for further development of a high-performance computation method suitable for the dynamic disturbance and damage identification analysis of general cracked structures.

Article
Publication date: 2 May 2017

Rafael Castro-Triguero, Enrique Garcia-Macias, Erick Saavedra Flores, M.I. Friswell and Rafael Gallego

The purpose of this paper is to capture the actual structural behavior of the longest timber footbridge in Spain by means of a multi-scale model updating approach in conjunction…

Abstract

Purpose

The purpose of this paper is to capture the actual structural behavior of the longest timber footbridge in Spain by means of a multi-scale model updating approach in conjunction with ambient vibration tests.

Design/methodology/approach

In a first stage, a numerical pre-test analysis of the full bridge is performed, using standard beam-type finite elements with isotropic material properties. This approach offers a first structural model in which optimal sensor placement (OSP) methodologies are applied to improve the system identification process. In particular, the effective independence (EFI) method is used to determine the optimal locations of a set of sensors. Ambient vibration tests are conducted to determine experimentally the modal characteristics of the structure. The identified modal parameters are compared with those values obtained from this preliminary model. To improve the accuracy of the numerical predictions, the material response is modeled by means of a homogenization-based multi-scale computational approach. In a second stage, the structure is modeled by means of three-dimensional solid elements with the above material definition, capturing realistically the full orthotropic mechanical properties of wood. A genetic algorithm (GA) technique is adopted to calibrate the micromechanical parameters which are either not well-known or susceptible to considerable variations when measured experimentally.

Findings

An overall good agreement is found between the results of the updated numerical simulations and the corresponding experimental measurements. The longitudinal and transverse Young's moduli, sliding and rolling shear moduli, density and natural frequencies are computed by the present approach. The obtained results reveal the potential predictive capabilities of the present GA/multi-scale/experimental approach to capture accurately the actual behavior of complex materials and structures.

Originality/value

The uniqueness and importance of this structure leads to an intensive study of its structural behavior. Ambient vibration tests are carried out under environmental excitation. Extraction of modal parameters is obtained from output-only experimental data. The EFI methodology is applied for the OSP on a large-scale structure. Information coming from several length scales, from sub-micrometer dimensions to macroscopic scales, is included in the material definition. The strong differences found between the stiffness along the longitudinal and transverse directions of wood lumbers are incorporated in the structural model. A multi-scale model updating approach is carried out by means of a GA technique to calibrate the micromechanical parameters which are either not well-known or susceptible to considerable variations when measured experimentally.

Details

Engineering Computations, vol. 34 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 3 July 2009

Haydar Uyanık and Zahit Mecitoğlu

The purpose of this paper is to develop a structural vibration control system by using a state observer which estimates system states using displacements measured from sensors.

Abstract

Purpose

The purpose of this paper is to develop a structural vibration control system by using a state observer which estimates system states using displacements measured from sensors.

Design/methodology/approach

Friedlander's exponential decay function is used for expressing the blast load model. A semiloof shell element is developed in order to account for piezoelectric effects. The composite plate is discretized by using the semiloof shell elements, and stiffness and mass matrices of the plate are obtained from the finite element model. In order to reduce the degrees of freedom of the finite element model, mode summation method is used with weighted modal vector including initial dominant modes in the dynamic behavior.

Findings

The structural vibrations are suppressed successfully and in an optimal way by using a state observer control system which estimates system states using displacements measured from sensors.

Originality/value

This paper shows, for the first time, that vibrations of a cantilevered composite plate subjected to blast loading are suppressed by the use of piezoelectric actuators. The state observer and optimal linear quadratic regulator are both used at the same time to suppress the vibrations.

Details

Aircraft Engineering and Aerospace Technology, vol. 81 no. 4
Type: Research Article
ISSN: 0002-2667

Keywords

Article
Publication date: 28 February 2023

Natalia García-Fernández, Manuel Aenlle, Adrián Álvarez-Vázquez, Miguel Muniz-Calvente and Pelayo Fernández

The purpose of this study is to review the existing fatigue and vibration-based structural health monitoring techniques and highlight the advantages of combining both approaches.

Abstract

Purpose

The purpose of this study is to review the existing fatigue and vibration-based structural health monitoring techniques and highlight the advantages of combining both approaches.

Design/methodology/approach

Fatigue monitoring requires a fatigue model of the material, the stresses at specific points of the structure, a cycle counting technique and a fatigue damage criterion. Firstly, this paper reviews existing structural health monitoring (SHM) techniques, addresses their principal classifications and presents the main characteristics of each technique, with a particular emphasis on modal-based methodologies. Automated modal analysis, damage detection and localisation techniques are also reviewed. Fatigue monitoring is an SHM technique which evaluate the structural fatigue damage in real time. Stress estimation techniques and damage accumulation models based on the S-N field and the Miner rule are also reviewed in this paper.

Findings

A vast amount of research has been carried out in the field of SHM. The literature about fatigue calculation, fatigue testing, fatigue modelling and remaining fatigue life is also extensive. However, the number of publications related to monitor the fatigue process is scarce. A methodology to perform real-time structural fatigue monitoring, in both time and frequency domains, is presented.

Originality/value

Fatigue monitoring can be combined (applied simultaneously) with other vibration-based SHM techniques, which might significantly increase the reliability of the monitoring techniques.

Details

International Journal of Structural Integrity, vol. 14 no. 2
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 12 February 2019

Frank Koenig, Pauline Anne Found and Maneesh Kumar

The purpose of this paper is to present the findings of a recent study conducted with the objective of addressing the problem of failure of baggage carts in the high-speed baggage…

Abstract

Purpose

The purpose of this paper is to present the findings of a recent study conducted with the objective of addressing the problem of failure of baggage carts in the high-speed baggage tunnel at Heathrow Terminal 5 by the development of an innovative condition-based maintenance system designed to meet the requirements of twenty-first century airport systems and Industry 4.0.

Design/methodology/approach

An empirical experimental approach to this action research was taken to install a vibration condition monitoring pilot test in the north tunnel at Terminal 5. Vibration data were collected over a 6-month period and analysed to find the threshold of good quality tires and those with worn bearings that needed replacement. The results were compared with existing measures to demonstrate that vibration monitoring could be used as a predictive model for condition-based maintenance.

Findings

The findings demonstrated a clear trend of increasing vibration velocity with age and use of the baggage cart wheels caused by wheel mass unbalanced inertia that was transmitted to the tracks as vibration. As a result, preventative maintenance is essential to ensure the smooth running of airport baggage. This research demonstrates that a healthy wheel produces vibration of under 60 mm/s whereas a damaged wheel measures up to 100 mm/s peak-to-peak velocity and this can be used in real-time condition monitoring to prevent baggage cart failure. It can also run as an autonomous system linked to AI and Industry 4.0 airport logic.

Originality/value

Whilst vibration monitoring has been used to measure movement in static structures such as bridges and used in rotating machinery such as railway wheels (Tondon and Choudhury, 1999) this is unique as it is the first time it has been applied on a stationary structure (tracks) carrying high-speed rotating machinery (baggage cart wheels). This technique has been patented and proven in the pilot study and is in the process of being rolled out to all Heathrow terminal connection tunnels. It has implications for all other airports world-wide and, with new economic sensors, to other applications that rely on moving conveyor belts.

Details

Journal of Quality in Maintenance Engineering, vol. 25 no. 3
Type: Research Article
ISSN: 1355-2511

Keywords

Article
Publication date: 22 December 2022

Yongliang Wang

In this paper, a superconvergent patch recovery method is proposed for superconvergent solutions of modes in the finite element post-processing stage of variable geometrical…

Abstract

Purpose

In this paper, a superconvergent patch recovery method is proposed for superconvergent solutions of modes in the finite element post-processing stage of variable geometrical Timoshenko beams. The proposed superconvergent patch recovery method improves the solution speed and accuracy of the finite element analysis of a curved beam. The free vibration and natural frequency of the beam were considered for studying forced vibrations and structural resonance. Beam vibration mode analysis was performed for high-precision vibration mode solutions and frequency values. The proposed method can be used to compute beam vibration modes of beams with different shapes and boundary conditions as well as variable cross sections and curvatures. The purpose of this paper is to address these issues.

Design/methodology/approach

An adaptive method was proposed to analyse the in-plane and out-of-plane free vibrations of the variable geometrical Timoshenko beams. In the post-processing stage of the displacement-based finite element method, the superconvergent patch recovery method and high-order shape function interpolation technique were used to obtain the superconvergent solution of mode (displacement). The superconvergent solution of mode was used to estimate the error of the finite element solution of mode in the energy form under the current mesh. Furthermore, an adaptive mesh refinement was proposed by mesh subdivision to derive an optimised mesh and accurate finite element solution to meet the preset error tolerance.

Findings

The results computed using the proposed algorithm were in good agreement with those computed using other high-precision algorithms, thus validating the accuracy of the proposed algorithm for beam analysis. The numerical analysis of parabolic curved beams, beams with variable cross sections and curvatures, elliptically curved beams and circularly curved beams helped verify that the solutions of frequencies were consistent with the results obtained using other specially developed methods. The proposed method is well suited for the mesh refinement analysis of a curved beam structure for analysing the changes in high-order vibration mode. The parts where the vibration mode changed significantly were locally densified; a relatively fine mesh division was adopted that validated the reliability of the mesh optimisation processing of the proposed algorithm.

Originality/value

The proposed algorithm can obtain high-precision vibration solutions of variable geometrical Timoshenko beams based on more optimized and reasonable meshes than the conventional finite element method. Furthermore, it can be used for vibration problems of parabolic curved beams, beams with variable cross sections and curvatures, elliptically curved beams and circularly curved beams. The proposed algorithm can be extended for application in superconvergent computation and adaptive analysis of finite element solutions of general structures and solid deformation fields and used for adaptive analysis of more complex plates, shells and three-dimensional structures. Additionally, this method can analyse the vibration and stability of curved members with crack damage to obtain high-precision vibration modes and instability modes under damage defects.

Details

Engineering Computations, vol. 40 no. 1
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 7 September 2012

Bernhard Weilharter, Oszkár Bíró and Siegfried Rainer

The purpose of this paper is to analyse the surface vibrations of an induction machine due to force waves acting on the stator and rotor core. The focus lies on the investigation…

Abstract

Purpose

The purpose of this paper is to analyse the surface vibrations of an induction machine due to force waves acting on the stator and rotor core. The focus lies on the investigation of the influence of force waves with axial variation and with higher spatial ordinal numbers on the surface vibration of an induction machine and thus its emitted noise.

Design/methodology/approach

Unit force waves with different spatial ordinal numbers and varying in axial direction are set up and applied on the stator and rotor teeth of a structural finite element model of an induction machine. Structural harmonic analyses with different frequencies are performed and the deformation of the machine is determined. After that, the root mean square of the normal component of the velocity on the surface of the machine's housing is determined and compared for the different force waves.

Findings

The influence of force waves with spatial ordinal numbers of higher order can have a significant influence on the structural vibration, especially if the spatial ordinal number is near the number of teeth. Furthermore, it is shown that the structure may react sensitively to axial variations of the forces, particularly near distinct structural resonances.

Originality/value

The presented investigations show relevant issues influencing the noise behaviour of electrical machines.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 1 May 2000

Jaroslav Mackerle

A bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical…

3543

Abstract

A bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view is given. The bibliography at the end of the paper contains 1,726 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1996‐1999.

Details

Engineering Computations, vol. 17 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 February 1993

E. HINTON, M. ÖZAKÇA and N.V.R. RAO

This paper deals with structural shape optimization of vibrating prismatic shells and folded plates. The finite strip method is used to determine the natural frequencies and modal…

Abstract

This paper deals with structural shape optimization of vibrating prismatic shells and folded plates. The finite strip method is used to determine the natural frequencies and modal shapes based on Mindlin‐Reissner shell theory which allows for transverse shear deformation and rotatory inertia effects. An automated optimization procedure is adopted which integrates finite strip analysis, parametric cubic spline geometry definition, automatic mesh generation, sensitivity analysis and mathematical programming methods. The objective is to maximize the fundamental frequency by changing thickness and shape design variables defining the cross‐section of the structure, with a constraint that the total volume of the structure remains constant. A series of examples is presented to highlight various features of the optimization procedure as well as the accuracy and efficiency of finite strip method.

Details

Engineering Computations, vol. 10 no. 2
Type: Research Article
ISSN: 0264-4401

Keywords

1 – 10 of over 4000